The disclosure relates to casting of turbine engine components. More particularly, the disclosure relates to casting of superalloy components with internal cooling passageways.
Gas turbine engine hot section components such as turbine blades, vanes, and air seals are often cast from superalloys (e.g., nickel-based or cobalt based). They are often cast over cores such as molded ceramic cores. Alternative cores include refractory metal cores (RMC) and RMC/ceramic core assemblies).
After casting, a deshelling and decoring process leaves the internal cooling passageways where the cores had been.
It may be desired to apply a thermal barrier coating (TBC) system to the casting.
Coating along the internal passageways poses difficulties.
U.S. Pat. Nos. 6,929,054, 7,207,373, and 7,207,374 disclose alumina protective coatings on RMCs.
U.S. Pat. No. 7,802,613 discloses noble metal plating of ceramic cores (and of ceramic-coated RMCs) to improve wetting by the superalloy during casting.
US Patent Application Publication 2005/0241797A1 discloses transferring an MCrAlY coating from a ceramic core to a superalloy casting.
U.S. Pat. No. 7,055,574 discloses transferring a yttria-stabilized zirconia (YSZ) coating layer and an MCrAlY layer from a sand core to a cast article.